A variety of warewashing detergents have been in common use in wash water solution at high temperature (temperature sanitizing) or low temperature (chemical sanitizing) for many years in both institutional and household automatic warewashing machines. Such detergents have taken the form of a thickened liquid, particulate solid, a pellet, aqueous solution or dispersion or in the form of a solid block detergent. In institutional warewashing, such particulate, pellet or solid block detergents are dispensed using an automatic dispenser that creates an aqueous concentrate (i.e.) an aqueous solution or suspension of the alkaline detergent using a water spray. The water spray dissolves a portion of the detergent when needed to for the aqueous concentrate. The aqueous concentrate is directed into a washing chamber in the automatic warewashing machine for a wash cycle. Such detergents have been based on a variety of sources of alkalinity including alkali metal hydroxide, alkali metal silicate, alkali metal carbonate or bicarbonate, etc.
During the wash cycle, the organic or inorganic components of the aqueous warewashing detergent effectively remove soil from ware. Detergent additives provide other functionality to the detergent such as water treatment, defoaming, etc. After cleaning with the detergent, the ware is commonly rinsed using an aqueous rinse composition made through the intentional combination of a rinse agent and an aqueous diluent. An aqueous rinse composition typically comprises a major proportion of water and about 50 to 400 parts of an active rinse agent per million parts of the rinse water. Rinse agents are commonly nonionic surfactants that adjust the surface energy of the ware with respect to the water to promote sheeting and complete rinse water removal. Ware free of rinse water can then dry without spotting or streaking. In typical detergent processing, the use of a water rinse without a rinse agent typically produces ware having substantial streaking and spotting caused by aqueous residue derived from the rinse remaining on the dishes after the rinse cycle ends.
In an institutional automatic warewashing machine, rinse agents and alkaline detergents are intentionally added separately using dispensers designed for either a specific rinse agent or a detergent. As set forth below, rinse agents are primarily nonionic surfactant materials. Rinse agents are typically a subset of the alkylene oxide polymeric nonionic materials and have unique properties that promote sheeting action in rinse water to avoid spotting and streaking. Not all nonionic materials are appropriate for rinsing use. Rinse agents should change the energy at the interface between the washed ware and the rinse water such that the rinse water is removed completely from the surface of the ware. Such an interface energy must be reduced to prevent the adhesion of water droplets to the washed ware surface. Further, rinse agents should be low foaming to prevent machine pump cavitation caused by high levels of foam.
Automatic warewashing machines used in a variety of institutional and industrial locations come in a large variety of embodiments. The simplest machines are typically machines operating at low temperature (less than 160.degree. F.) having a single tank for aqueous materials used in the wash cycle. Such low temperature machines typically use a washing cycle that uses a washing solution prepared from an alkaline detergent composition. Once the short washing cycle is complete, the washing liquid is typically dumped from the machine and the ware is rinsed using a rinse cycle. The rinse water is typically maintained in the machine for reuse in the next wash cycle. To create a proper wash water material, additional detergent is typically dispensed into the water to restore the appropriate concentration of the washing ingredient components. After the wash to washing and rinsing cycles are complete, the ware can be contacted with the sanitizer material to ensure complete safety. Larger multistation high temperature machines (greater than about 160.degree. C.) are also used in locations having a higher volume of ware cleaning. Such machines typically involve a conveyor system in which individual racks of ware are moved through the multistation machine for a complete washing regimen. Often such ware racks are prescrubbed to remove large gross soils in a prewasher/prescrape stage, the ware is contacted with water under pressure to remove all large food items prior to washing. In the large rack conveyor systems, the ware and rack are typically exposed to a prewash stage, a power wash stage, a power rinse stage, a final rinse stage and can be exposed to a blow dryer to complete the production of a clean dry dish. Prewash stage is often involved contacting the ware with aqueous streams containing moderate amounts of cleaner materials to clean or prepare soils for removal. In a power wash stage, the ware is contacted with aqueous detergents containing effective concentrations of alkaline materials, surfactants and other components to completely remove the soils and prepare for the power wash stage in the prewash stage. The ware is then often directed to a power rinse stage and a final rinse stage. In these rinse stages, the alkaline detergent materials are rinsed from the dishes and if necessary, the ware can be exposed to a sanitizer rinse. In order to ensure that no confusion results from the discussion of the warewashing machines, simple dump and fill, single zone dishwashers can be operated at both high and low temperature. Similarly, large conveyor systems can also be operated at high or low temperature. These warewashing machines can also have a variety of other elements including conveyor units, drive units, storage locations, waste system disposals, racks, etc. Further, the reuse or recycling of rinse water is also common in both high and low temperature machines. The relatively clean rinse water that remains after rinsing is complete is often recycled to a wash tank for the purpose of creating a wash solution using an alkaline concentrate containing the wash chemicals.
Rinse agents used in machine rinse cycles have a polymer composition that is optimized to provide rinsing properties that have relatively reduced surfactancy, soil removing properties or other properties common to nonionic materials in general. A conventional rinse agent is typically formulated as a concentrate in liquid or solid form which is diluted with water in a rinse aid dispenser to form an aqueous rinse composition used in a warewashing machine rinse cycle to ensure that dishes sheet cleanly. The requirement for a separate rinse dispenser adds additional expense and complexity to institutional warewashing machines. This is particularly true in smaller low temperature machines having a single station that is used for all cycles in a warewashing regimen. In the low temperature machine, a rinse cycle follows a wash cycle and the rinse water is typically retained, combined with detergent and used in the washing cycle. After the washing cycle is complete the water is then directed to a machine drain. Low temperature machines are typically used in relatively small volume warewashing locations. Such locations require relatively simple operating machines with minimal moving parts and minimal upkeep and maintenance. Larger installations, having conveyor type machines that clean a large volume of ware, often on a 24 hour a day basis, also have a need for an easily used warewashing machine and warewashing chemicals. Accordingly a need has existed in this art to reduce the amount of chemicals stored and used in warewashing locations using either a relatively simple low temp machine or a relatively complex high temp conveyor-type machine.